Cigarette lighter with a fusible circuit breaker

ABSTRACT

A cigarette lighter of the type having a manually removable igniting plug slidably received in the open end of a mounting case which includes a current inlet supply post for completing an igniting circuit between a heating element carried by the igniting plug and a connector from a current source. The current inlet supply post includes a fusible pin formed of a low-melting point alloy which melts by conductive heating so as to permanently interrupt the igniting circuit by releasing an end portion of the pin and the connector from said post when the lighter reaches a predetermined elevated temperature.

United States Patent [72] Inventors Donald G. Dening Rochester; Jack P. Castellana, Churchville, N.Y. [21] Appl. No. 864,314 [22] Filed Oct. 7, 1969 [45] Patented Apr. 6, I971 [73] Assignee General Motors Corporation Detroit, Mich.

[54] CIGARETTE LIGHTER WITH A FUSIBLE CIRCUIT BREAKER 3 Claims, 2 Drawing Figs.

[52] US. Cl 219/265, 219/517, 200/3, 337/6 [51] Int. Cl F23g 7/24 [50] Field of Search 219/262, 263-9, 264-5, 517, 253; 200/6108, 3; 337/4-8, 66, 142

[56] References Cited UNITED STATES PATENTS 2,168,815 8/1939 Wood 2l9/517X Primary ExaminerVolodymyr Y. Mayewsky Attorneys-J. L. Carpenter and E. J Biskup ABSTRACT: A cigarette lighter of the type having a manually removable igniting plug slidably received in the open end of a mounting case which includes a current inlet supply post for completing an igniting circuit between a heating element carried by the igniting plug and a connector from a current source. The current inlet supply post includes a fusible pin fonned of a low-melting point alloy which melts by conductive heating so as to permanently interrupt the igniting circuit by releasing an end portion of the pin and the connector from said post when the lighter reaches a predetermined elevated temperature.

CIGARETTE LIGHTER WITH A FUSIBLE CIRCUIT BREAKER In lighters of the type commonly used in motor vehicles, a manually removable igniting plug carrying a heating element is adapted to be supported in a cylindrical case mounted on the vehicle instrument panel. When it is desired to effect closure of an igniting circuit to the heating element, the igniting plug is pushed further into the case to an energizing igniting position where it is held by thermostatically responsive bimetallic fingers which are carried by an inlet supply post connected to a suitable source of current, such as an automobile battery. The fingers serve as latch means to maintain the igniting circuit to the heating element until the latter reaches a predetermined igniting temperature, at which point the fingers deflect inwardly and the igniting plug is automatically released to permit removal for use.

Normally, the heating element reaches an incandescent red heat of around l400 F. in about to seconds. Because of the relatively high power consumption required to attain this performance, there is an attendant possibility of excessive heating if the igniting circuit remains closed for a prolonged period such as would occur if the bimetallic fingers fail to release at the igniting temperature. Therefore, it has been found desirable to provide a current interrupting device for preventing sustained malfunctioning of the lighter of the type which will cause permanent structural and electrical damage due to overheating.-

The present invention contemplates providing the current inlet to the igniting circuit with a fusible joint to preclude damage of the aforementioned type. This is accomplished by incorporating a fusible pin on an outwardly projecting end of the current inlet supply post. The pin is formed of a low temperature melting alloy which is adapted to melt into separate parts when the lighter reaches a predetermined elevated temperature. The terminal end of this pin is attached to a connector which is wired to a suitable source of power. The connector is sheathed by a nonconductive sleeve so that as the pin fuses into separate pieces, the terminal end and the connector mechanically separate from the mounting case so as to permanently interrupt the igniting circuit to the heating element. The sleeve serves to insulate the lead wire and prevent any secondary electrical contact between the conductive surfaces on the instrument panel.

By incorporating the fusible pin at the current inlet, the circuit-breaking feature is responsive to the malfunctioning of all of the lighter components rather than selected portions as might be the case if the circuit breaking means were located interior of the case or plug. This arrangement also requires that the cause of the malfunctioning of the assembly be corrected before the lighter can be reused and, inasmuch as the malfunctioning usually occurs in and causes permanent damage to components of the case, it is deemed advisable and the preferred embodiment contemplates replacement of the entire case after melting of the pin.

Accordingly, it is an object of the present invention to provide a new and improved cigarette lighter which incorporates a fusible inlet in advance of the lighter case for preventing excessive overheating.

Another object of the present invention is to provide a cigarette lighter having a fusible element which is adapted to melt and permanently interrupt the lighter igniting circuit and electrically separate the entire lighter from the source of electrical power at a predetermined elevated temperature.

It is another object of the present invention to provide a circuit breaker for a cigarette lighter wherein a fusible pin incorporated on the current inlet supply post of the lighter mounting case has an outwardly projecting end that is adapted to be attached to a connector wired to a current source, the fusible pin being formed of a low-melting point alloy which melts and fuses into separate pieces at a predetermined elevated temperature to mechanically and electrically separate the connector from the lighter.

It is a further object of the present invention to provide a cigarette lighter of the type having a mounting case having an open end forthe receipt of a manually removable igniting unit carrying a heating element which, in an energizing position, is electrically connected to a current source by a current inlet supply post having an outwardly projecting end on which a fusible member is removably carried, the fusible member being adapted to melt at a predetermined elevated tempera ture of the assembly so as to permanently interrupt the igniting circuit to the heating element and mechanically separate the inlet post from the current source.

It is a more specific object of the present invention to provide a cigarette lighter of the type having an igniting plug including a heating element slidably received in the open end of a mounting case wherein a current inlet supply post in the lighter-igniting circuit and carried by the case has a bore formed in an outwardly projecting end thereof in which a fusible cylindrical pin is retained, the pin being connected by a sheathed connector to a current source and being adapted to progressively melt upon conductive heating until the connector mechanically separates from the post so as to permanently interrupt the igniting circuit.

These and other objects will be apparent to one skilled in the art upon reading the following detailed description, reference being made to the accompanying drawings in which:

FIG. 1 is a partially. sectioned side elevational view of a cigarette lighter made in accordance with the present invention; and

FIG. 2 is an enlarged cross-sectional view of the current inlet supply post shown in FIG. 1.

Referring to the drawings, there is shown a cigarette lighter 10 comprising a generally tubular metallic mounting case 12 having an open end 14 which removably receives an igniting plug 16. The mounting case 12 may be secured by any well known matter to a support such as a vehicle instrument panel such that the open end 14 will be substantially flush with the front surface of the panel with the remainder of the case 12 projecting rearwardly thereof.

The igniting plug 16 generally comprises a cylindrical metallic sleeve 20 which surrounds an interior contact cup 22. A coiled resistive heating element 24 is disposed within the contact cup 22 and electrically connected in series by any suitable means between the latter and the sleeve 20. The heating element 24, the sleeve 20, and the contact cup 22 are suitably secured to an operating knob 26. The sleeve 20 of the igniting plug 16 is slidably received in the bore 28 defined by the inner cylindrical surface of the case 12 and is frictionally held therein by a plurality of radially inwardly extending spring fingers 30. The forward end of the contact cup 22 includes a radially inwardly directed annular indentation 32 which serves as a movable latch means for cooperation with fixed temperature responsive latch means mounted interior of a mounting case. By inwardly pushing the igniting plug 16 further into the bore 28, the heating element 24 can be internally moved between the illustrated idle position and an energizing position to be hereafter described.

The rearward end of the mounting case 12 includes an inwardly extending well defined by a cylindrical wall 34 and a circular base 36. A central aperture is formed in the base 36 in which a current inlet supply post 38 is received and retained. A generally U-shaped bimetallic latch 40 having fingers 41 is fixedly connected to the inner end of the post 38 at a riveted head 42. Each finger 41 includes a radially inwardly directed indentation 44 which is adapted to selectively engage the annular indentation 32 on the contact cup 22 under control of the user for establishing an energizing position for the heating element 24 and completing an igniting circuit for the lighter 10. The inlet supply post 38 is aligned on and electrically insulated from the base 36 by a pair of metallic washers 46,48 which are held in spaced relationship from the base 36 by insulating washers 50,52. The inlet post 38 is staked at 53 to fixedly clamp the former and the aforementioned washers to the base 36.

A substantially cup-shaped ejector 60, open at both ends,.is slidably disposed about the wall 34 within the case 12. ,A

coiled spring 62 is disposed interior of the case 12 between the rear surface of the latter and an annular flange 64 on the ejector 60. In the idle position when an igniting circuit is not completed to the heating element 24, the spring 62 biases the ejector 60 to an extended forward position in abutment with the outer periphery of the washer 50.

The assembly thus far described functions as follows. ln an idle position of the lighter 10, the sleeve 20 of the igniting plug 16 is frictionally held to the case 12 by the spring fingers 30 in a noncircuit establishing relationship. If the user desires to energize the heating element 24 to an igniting temperature, he pushes the knob 26 inwardly until the indentations 32 latchingly engage the indentations 44 thereby establishing an igniting circuit from the current through the inlet post 38, the latch 40, the heating element 24, the contact cup 22, the outer sleeve 20, the case 12, and the ground 54. Upon the heating element 24 reaching a predetermined igniting temperature, the fingers of the latch 40 deflect inwardly toward the longitudinal axis of the case 12 thereby disengaging the latched condition to permit the spring 62 and the ejector 60 to project the igniting plug 16 outwardly so that the user may remove the latter for use. During usage of the lighter, the igniting circuit for one reason or another may short circuit or may be energized for a prolonged period of time-both of which conditions may result in elevated temperatures that can cause permanent electrical and structural damage to the assembly and surrounding areas. To preclude this possibility, and as shown in FIG. 2, the present lighter includes a cylindrical pin 70 that is removably retained within a bore 72 formed in the outwardly projecting end 74 of the inlet post 38. The pin 70 is formed of a low melting point alloy which is adapted to melt at a predetermined elevated temperature of the lighter 10. For example, the above described lighter has been successfully tested using the fusible pin consisting by weight of an alloy containing l percent (l0 percent) bismuth, 40 percent (40 percent) lead, and 50 percent (50 percent) tin and having a melting range of 260 F.--290 F. The pin 70 has an inlet end 76 which is retained in the bore 72 and a terminal end 78 which projects outwardly of the post 38.

A lead wire 80 which is adapted to be electrically connected to a suitable current source such as the automotive battery includes a connector 82 which is pressed over the outer surface of the pin 70. A cylindrical sleeve 84 exteriorly covers the terminal end 78 of the pin 70 and the connector 82. Should the lighter malfunction, the temperature of the case 12 would progressively increase until such time as the melting point of the pin 70 is reached. When this occurs, the pin 70 melts in the vicinity of the projecting end 74 and thereafter, the terminal end 78 drops away from the inlet post 38. The outer sleeve 84 serves to shield the connector 82 after this circuit-breaking action thereby preventing any inadvertent secondary electrical circuit through an adjacent metallic part. In lighters incorporating fusible pins 70 of the aforementioned material, tests have indicated that at 14.2 volts a 0.155 inch diameter pin will consistently melt such that the connector 82 will separate from the inlet post 38 in approximately 1.5 minutes.

Experience has shown that the noted malfunctioning of the lighter is most often traced to a breakdown or failure in the interior pans of the case 12 and, when as assembly temperature that is sufficient to melt the pin 70 has occurred, there is likely to be permanent structural and electrical damage to these components. Therefore, the present invention contemplates that the case 12 be replaced although it will be apparent that the interior portion of the pin 70 could be removed from the bore 72 and a new stud located therein so that the lighter would be ready for reuse. Furthermore, it will be appreciated that the assembly could be so constructed so as to require only replacement of an adapter removably carried between the inlet post 38 and the fusible portion. It will, of course, be understood that we do not, desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

We claim: l. A cigarette lighter comprlsingz a generally tubular case having an open end and a closed end; an igniting unit including a heating element received in said open end and manually movable therewithin to an igniting position for energizing said heating element; a current inlet supply member carried by and electrically insulated from said closed end, said current inlet supply member having a first portion projecting interior of said case and a second portion projecting outwardly thereof; an aperture formed in said second portion; a fusible pin having a first end retained in said aperture and a second end projecting outwardly thereof, said pin being formed of a low-melting point alloy which is adapted to melt by conductive heating and fuse into separate ends at a predetermined elevated temperature; connector means attached to one of said ends and adapted to be connected to a current source; conducting means carried by said case and said igniting unit which are engageable at said igniting position so as to complete an electrical circuit between said current source and said heating element for energizing the latter, the arrangement being such that over-energization of said heating element will result in said fusible pin reaching said predetermined elevated temperature and melting into said separate ends thereby interrupting said electrical circuit to said heating element by mechanically and electrically separating said connector means from said current inlet supply member and said case.

2. A cigarette lighter comprising: a generally tubular mounting case having an open end and a closed end; an igniting plug slidably received in said open end; a heating element carried by said igniting plug and internally movable within said case to igniting position for energizing the heating element; a current inlet supply post carried by and electrically insulated from said closed end, said current inlet supply post having a first end projecting interior of said case and a second end projecting outwardly of said case; an axial bore formed in said second end of said current inlet support post; a cylindrical pin having an inlet end removably retained in said bore and a terminal end projecting outwardly of said current inlet supply post, said pin being formedof a tin-lead-bismuth alloy having a low melting point so as to fuse upon conductive heating into separate ends at a predetermined elevated temperature; a connector attached to said terminal end of said pin and adapted to be connected to a current source; an insulating sleeve externally covering said terminal end of said pin and said connector; a latch member attached to said first end of said current inlet supply post engageable at said igniting position with said igniting plug so as to complete an electrical circuit between said current source and said heating element until the latter reaches a predetermined igniting temperature whereby over energization of the heating element causes said pin upon reaching said predetermined elevated temperature to melt until said connector mechanically separates from said current inlet supply post to thereby interrupt said electrical circuit whereupon said sleeve shields said conductor to prevent an inadvertent secondary electrical circuit through an adjacent conductive member.

3. The invention recited in claim 2 wherein said pin comprises substantially ten percent (10 percent) bismuth, 40 percent (40 percent) lead, and 50 percent (50 percent) tin and has a melting point ranging between 260 F. to 290 F. 

1. A cigarette lighter comprising: a generally tubular case having an open end and a closed end; an igniting unit including a heating element received in said open end and manually movable therewithin to an igniting position for energizing said heating element; a current inlet supply member carried by and electrically insulated from said closed end, said current inlet supply member having a first portion projecting interior of said case and a second portion projecting outwardly thereof; an aperture formed in said second portion; a fusible pin having a first end retained in said aperture and a second end projecting outwardly thereof, said pin being formed of a low-melting point alloy which is adapted to melt by conductive heating and fuse into separate ends at a predetermined elevated temperature; connector means attached to one of said ends and adapted to be connected to a current source; conducting means carried by said case and said igniting unit which are engageable at said igniting position so as to complete an electrical circuit between said current source and said heating element for energizing the latter, the arrangement being such that over-energization of said heating element will result in said fusible pin reaching said predetermined elevated temperature and melting into said separate ends thereby interrupting said electrical circuit to said heating element by mechanically and electrically separating said connector means from said current inlet supply member and said case.
 2. A cigarette lighter comprising: a generally tubular mounting case having an open end and a closed end; an igniting plug slidably received in said open end; a heating element carried by said igniting plug and internally movaBle within said case to igniting position for energizing the heating element; a current inlet supply post carried by and electrically insulated from said closed end, said current inlet supply post having a first end projecting interior of said case and a second end projecting outwardly of said case; an axial bore formed in said second end of said current inlet support post; a cylindrical pin having an inlet end removably retained in said bore and a terminal end projecting outwardly of said current inlet supply post, said pin being formed of a tin-lead-bismuth alloy having a low melting point so as to fuse upon conductive heating into separate ends at a predetermined elevated temperature; a connector attached to said terminal end of said pin and adapted to be connected to a current source; an insulating sleeve externally covering said terminal end of said pin and said connector; a latch member attached to said first end of said current inlet supply post engageable at said igniting position with said igniting plug so as to complete an electrical circuit between said current source and said heating element until the latter reaches a predetermined igniting temperature whereby over energization of the heating element causes said pin upon reaching said predetermined elevated temperature to melt until said connector mechanically separates from said current inlet supply post to thereby interrupt said electrical circuit whereupon said sleeve shields said conductor to prevent an inadvertent secondary electrical circuit through an adjacent conductive member.
 3. The invention recited in claim 2 wherein said pin comprises substantially ten percent (10 percent) bismuth, 40 percent (40 percent) lead, and 50 percent (50 percent) tin and has a melting point ranging between 260* F. to 290* F. 